Rotary switches, controllers, encoders potentiometers, and the like (hereinafter also referred to as "rotary switch devices") conventionally include both rotating parts and stationary parts therein. They are usually mounted on the rear surface of the front panel of an apparatus which is to be controlled and they include a rotary shaft that passes through an aperture in such panel. A control knob is usually fastened to the outer end of the rotary shaft. Examples of rotary switch devices of this type may be seen in U.S. Pat. Nos. 3,226,496 to Seabury, Jr., and U.S. Pat. No. 4,246,452 to Chandler. Such rotary switch devices, although capable of functioning satisfactorily, have unnecessarily limited useful service lives due to the facts that they have internal terminals that frictionally contact, and move with respect to, other internal parts, and that the interiors thereof are in communication with ambient atmosphere through the apertures in the front panel. Accordingly, the internal terminals and other internal parts contacted thereby are subject to frictional wear; any contaminants that are in the atmosphere may reach and adversely affect the interiors of the rotary switch devices; and uninhibited oxidation of the inner operating mechanisms of the devices may also take place, in each case limiting the effective service life of the affected device. In addition, the need for panel apertures to be employed in connection with rotary switch devices has limited the use of such devices in sensitive equipment (e.g., medical testing equipment) that is required to be isolated from ambient atmosphere during its use.
Consideration has heretofore been given to sealing the interiors of linear, as distinguished from rotary, switch devices. Examples of such sealed linear switch devices may be seen in U.S. Pat. No. 3,777,222 to Harris, U.S. Pat. No. 3,895,288 to Lampen et al., U.S. Pat. No. 4,217,473 to Parkinson, and U.S. Pat. No. 4,317,970 to Hafner et al. In linear switch devices of the foregoing type a flexible membrane sealingly covers an underlying switch mechanism, and depression of the membrane at an appropriate point on its surface causes the underlying switch contacts to close. Although sealed switch devices of the foregoing type provide satisfactory operation over long service lives, the constructions employed are not applicable to rotary switch devices.
It is, therefore, a primary object of the present invention to provide an improved rotary switch device.
Another object of the present invention is to provide an improved rotary switch device, the interior of which is sealed from communication with ambient atmosphere.
A further object of the present invention is to provide an improved rotary switch device that is essentially devoid of rotating parts but is, nevertheless, capable of sensing rotary hand motion made with respect thereto and providing an output signal corresponding to such movement.
Additional objects and advantages of this invention will become apparent as the following description proceeds.